The invention relates to a method for the production of a formed sheet-metal component which is formed by internal high-pressure forming. The invention also relates to a formed component produced according to the method.
It is known to shape components by internal high-pressure forming of butt-welded tubular preforms which are cut from corresponding bar stock to the length required. From EP-A-0620056 it is also known to weld together a number of such butt-welded tubular preforms of different diameter and thickness into a single tube which is then formed into a tubular component by internal high-pressure forming.
Extended formed components made from tubular preforms may especially be used as components in motor vehicle construction. Here, these components usually have to be joined to other components, eg. by further welding or by bonding. For certain purposes, it is then necessary for one component to be provided with at least one attachment flange. At least one operation is required to add such a flange to the said components, which is a disadvantage in terms of cost, so that, in this case, several components formed by deep-drawing or pressing are usually welded together in a conventional manner into one formed component.
From EP-A-0589370 it is known to provide two essentially flat metal sheets with a conduit for introducing the fluid for the internal high-pressure forming, and to weld the sheets together at their edges; the result is a formed body with a surrounding flange, which is not desired in edges; the result is a formed body with a surrounding flange, which is not desired in many applications in motor vehicle construction. DE-C-900085 likewise discloses the internal high-pressure forming of two essentially flat metal sheets which have been both welded together and which have a chamber in the middle formed from two domes for the introduction of the pressure fluid. This also produces a formed body with a surrounding flange. Similarly, DE-A 3418691 shows the forming of two or four flat metal sheets which are joined together at their edges. U.S. Pat. No. 5,070,717 shows a flangeless butt-welded tube being formed in such a way that a flange is produced in the forming process. In this way it is possible to produce an extended formed body with a flange on one side only, but additional cutting and welding operations are necessary to obtain a flange form with a straight end face.
Therefore, the problem which the invention by internal high-pressure forming, provides a component which can easily be produced and be joined to other components, in particular an elongate component with a flange on one side only, or with two flanges on opposite sides of the component.
This object is achieved by forming a body from sheet metal with at least one flange extending outwardly from an edge region of the sheet metal, the flange being welded, and then transforming the body into a preform by means of internal high-pressure forming.
By firstly forming, by rounding, a tubular body with an outwardly directed flange, production is facilitated, since the flange serves as a welding flange which can be welded by conventional low-cost methods at a high rate of production. In the completed formed component, this already existing flange serves as an attachment point for other components, which makes the use of such a formed component advantageous in many applications in comparison with conventional bodies formed by internal high-pressure forming.
In an alternative solution, two half-rounded metal sheets each provided with two projecting flat tongues are first of all joined to form one essentially tubular body with two flanges.
Another object of the invention is to provide a component formed by internal high-pressure forming which can be easily joined to other components. This object is achieved with a formed component made from a sheet metal body provided with an outwardly projecting flange and molded into a shape by the application of internal high-pressure.